Vale of Glamorgan Council, which is yet to grant planning permission, said people had complained the building was already being used for teaching.

Ms Church denied the claims and insisted she was operating legally.

The council is yet to decide whether or not it will take formal action - but could in theory issue notices telling the singer to either stop or reverse any unauthorised work.

Ms Church plans to open a non-fee paying school for 20 local children aged nine to 12 which will be based at her home only for the first year.

The idea is part of The Awen Project, which she has set up and hopes will grow into a charity to set up other independent schools.

The Cardiff-born singer said it was aimed at children "who may have been struggling in mainstream education and providing an alternative that doesn't cost anything".

"We're trying to do something which is beneficial to the community," she added.

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Notices of a bid for planning permission for a school have been put up in Dinas Powys

Ms Church said a part-time home school tutoring group was currently using the annexe for less than 12.5 hours per week, which she says is approved by school inspectorate Estyn and the Welsh Government.